Fluid operated timer circuit



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NEE $8M 8 m 2 m United States Patent 3,276,689 FLUID OPERATED TIMERCIRCUIT John D. Freeman, Westport, Conn., assignor to General TimeCorporation, New York, N.Y., a corporation of Delaware Filed Aug. 14,1964, Ser. No. 389,711 4 Claims. (Cl. 235-201) The present inventionrelates generally to fluid-operated timers, more particularly, to.improved fluid-operated counter and adder circuits suitable for use in afluidoperated timer.

It is a primary object of the present invention to provide an improvedfluid-operated timer which is capable of measuring practically anypredetermined time interval in relatively small increments, such as inincrements of a tenth of a second or less. Another object is to providean improved fluid-operated timer which is extremely accurate, even overrelatively long time intervals.

It is a further object of the present invention to provide an improvedfluid-operated timer including a plurality of fluid-operated switchingelements for counting a sequence of timed fluid pulses at closeintervals. A related object is to provide such a timer wherein thefluid-operated switching elements respond extremely rapidly to the fluidpulses being counted. Another related object is to provide such a timerin which the timed fluid pulses being counted are applied directly toeach of the individual switching elements rather than being applied toonly a single switching element and then passed sequentially through theremaining switching elements. In this connection, it is an object toprovide such a timer in which the response time for any given pulse isthe response time of only a single fluid-operated switching elementrather than the cumulative response times of a plurality of suchelements.

It is still another object of the invention to provide an improvedfluid-operated timer in which each of the timed fluid pulses beingcounted produces a predetermined output signal from only a singlefluid-operated switching element. An allied object is to provide such atimer in which each timed fluid pulse produces a predetermined outputsignal by the switching of only a single fluidoperated switchingelement. A further object is to provide such a timer in which eachfluid-operated switching element is switched only once betweenresettings of the fluid-operated counter.

Yet another object of the present invention is to provide an improvedfluid-operated timer which is positive starting and which automaticallyresets itself. It is another object to provide such a timer which issimple to construct, having no moving parts, and is reliable even overextended periods of operation.

A still further object of the invention is to provide an improvedfluid-operated adder suitable for use in a fluidoperated timer and whichhas a low response time. Thus, it is an object to provide such an adderwhich produces the desired output signal without substantially extendingthe desired time interval. In this connection, it is an object toprovide such an adder which substantially increases the reliability andaccuracy of the present timer over fluid-operated timers of the priorart.

Other objects and advantages of the invention will become apparent uponreading the following description and appended claims and upon referenceto the drawings, in which:

FIGURE 1 is a partially diagrammatic plan view of an improvedfluid-operated counter circuit embodying the present invention;

FIG. 2 is a sectional side view of FIGURE 1 taken along section line2-2;

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FIG. 3 is a diagrammatic plan view of an improved fluid-operated addercircuit embodying the present invention; and

FIG. 4 is a diagrammatic plan view of a fluid-operated oscillatorsuitable for use in a completely fluid-operate timer including thecircuits of FIGS. 1 and 3.

While the invention will be described in connection with certainpreferred embodiments, it is to be understood that the invention is notto be limited to the disclosed embodiments but, on the contrary, it isintended to cover the various modifications and equivalent arrangementsincluded within the spirit and scope of the appended claims.

In the practice of the present invention, there is provided an improvedfluid-operated timer circuit comprising, in combination, a source ofpressurized fluid, a series of fluid-operated switching elements each ofwhich has a body defining a jet chamber having a power nozzle at one endconnected to the source of pressurized fluid to produce a power jet andhaving first and second output tubes at the other end, first and secondcontrol nozzles on opposite sides of the power nozzle for directing thepower jet toward the respectively opposite output tubes to define firstand second states of operation, means for applying timed fluid pulsesdirectly to the first control nozzle of each switching element forswitching each element from the first to the second state of operation,biasing means operatively associated with the second control nozzle ofeach switching element for selectively controlling the switching of theelements by the timed fluid pulses, the biasing means for each elementbeing responsive to the switching of the preceding element in the seriesso that the elements are switched sequentially in timed relation to saidtimed fluid pulses, and reset means for restoring the switching elementsto the first state of operation.

Thus, referring to FIG. 1, there is provided a fluidoperated timercircuit including a series of bi-stable fluid amplifiers 11, 12, 13, and14 preferably formed by three flat plates 15, 16, and 17, as shown inthe sectional view in FIG. 2. The plate 16, which is centrallycontoured, is positioned between the plates 15 and 17, and all threeplates are secured together by a plurality of machine screws 18. Theseplates may be composed of metal, plastic, or other suitable material.For the purpose of illustration, the plates are shown composed of clearplastic material. Although the plate structure is shown only for thefirst amplifier 11, it will be understood that the other threeamplifiers 12, 13, and 14 can be constructed in the same manner.

The configuration cut from the center plate 16 for each amplifierdefines a central power nozzle P which is fed from a fluid pressure line19. The pressurized fluid passes through the power nozzle P and issuestherefrom as a high energy power jet which passes between first andsecond control nozzles CL and CR through a jet chamber R. At the frontof the chamber for receiving the jet are first and second divergingoutput tubes 0L and OR separated by a divider D. It is a knownphenomenon in fluid operated amplifiers of the boundary-layer-controlledtype that the jet does not remain centered but tends to cling to one ofthe side walls of the chamber R, in accordance with the Bernoulliprinciple, so that the jet is directed into one of the output tubes.This represents one stable state of operation. In order to switch theamplifier to the other stable state, pressurized fluid is passed intothe control nozzle CL or CR nearest the power jet so as to provide acontrol jet which deflects the power jet over into the other outputtube. Although the boundary-layercontrolled type of fluid amplifier ispreferred in this invention, it will be understood that other types offluid amplifiers may be used.

As shown in FIG. 1, each of the intermediate amplifiers 12 and 13between the first and last amplifiers 11 and 14, respectively, also hasa secondary control nozzle S opening into the right hand output tube OR.This secondary control nozzle S operates in the same manner as thecontrol nozzle CR, so that the power jet can be switched from outputtube OR over into output tube L by applying pressurized fluid to eitherthe primary control nozzle CR or the secondary control nozzles.

For the purpose of actuating the bi-stable amplifiers 11 through 14,timed fluid pulses are passed through a line 20 which has a plurality ofbranches 21, 22, 23, and 24 each of which leads into the left handcontrol nozzle CL of one of the bistable amplifiers. Thus, it can beseen that the timed fluid pulses are continuously applied directly tothe left hand control nozzle CL of all four amplifiers. Before theapplication of the timed fluid pulses is commenced, the power jet ofeach of the four amplifiers is directed to-its left output tube OL.Then, when the timed fluid pulses are applied to the left hand controlnozzle CL, they tend to deflect the power jet away from tube 0L overinto tube OR.

However, as the power jet of the first amplifier 11 is dischargedthrough the output tube 0L1, a portion of the fluid is directed througha line 32 into the right hand control nozzle CR2 of the second amplifier12, the remainder of the fluid being dumped through the restrictedportion of 0L1. Similarly, fluid from output tube 0L2 of the secondamplifier 12 is directed through a line 33 to nozzle CR3 of the thirdamplifier 13, and fluid fro-m output tube 0L3 of the third amplifier isdirected through a line 34 to nozzle CR4 of the fourth amplifier 14.Thus, each of the amplifiers 12, 13 and 14 is biased to the left by thejets emerging from the control nozzles CR2, CR3 and CR4, and the firstamplifier .11 is the only amplifier that is conditioned for switching.In other words, amplifier 11 is the only one that is not biased. As aresult, although the first fluid pulse from the line 20 is applied toall four amplifiers, it switches only the first amplifier 11 bydeflecting the power jet from output tube 0L1 to output tube 0R1.

The right hand output tube 0R1 of the first amplifier 11 is connected toa manually adjustable selector valve, as described in more detailhereinafter. Thus, switching of the first amplifier 11 from tube 0L1 totube 0R1 removes the biasing fluid from control nozzle CR2, therebyconditioning the second amplifier 12 for switching. As a result, thesecond'fluid pulse from the line 20 switches the second amplifier 12 bydeflecting the power jet therein from tube 0L2 to tube 0R2. This in turnremoves the biasing fluid from control nozzle CR3, conditioning thethird amplifier 13 for switching, so that the third fluid pulse deflectsthe third power jet from tube 0L3 to tube 0R3. Finally, since thebiasing fluid from control nozzle CR4 has been removed by the switchingof amplifier 13, the \fourth pulse switches the fourth amplifier 14 fromtube 0L4 to tube 0R4.

It can be seen from the above description that the lines 32, 33 and 34and the right hand control nozzles CR2, CR3 and CR4 act as biasing orconditioning means which selectively control the switching of thebi-stable amplifiers by the timed fluid pulses from the line 20.Moreover, each of these biasing or conditioning means is responsive tothe switching of the preceding amplifier, so that the amplifiers areswitched sequentially in timed relation to the applied fluid pulses.However, it is important to note that only the biasing of each amplifieris controlled by the preceding amplifiers in the series, and that theactual switching of the amplifiers is effected by pulses applieddirectly from the line 20.

In accordance with one feature of this invention, in order to insurethat none of the applied fluid pulses switches two of the bi-stableamplifiers at the same time, small restrictions 32a, 33a and 34a areprovided in the biasing lines 32, 33 and 34, respectively, andcorresponding restrictions are provided in the ends of the output linesOL which feed the biasing lines. These restrictions act as time delaymeans so that some biasing fluid will continue to flow out of thecontrol nozzles CR for a short time after the pulses are removed.

For the purpose of resetting the four amplifiers to their originalstable states, a portion of the fluid from output tube 0R4 of the lastamplifier 14 is directed through a reset line 40. This reset line 40 hasthree branches 41, 42, and 43 which direct the resetting fluid to thenozzle CR1 of the first amplifier and the secondary control nozzles S2and S3 of the second and third amplifiers respectively. Thus, theresetting fluid deflects the power jet of each of the amplifiers 11, 12and 13 from output tube OR over into tube 0L, thereby restoring theseamplifiers to their original stable states. As the power jet ofamplifier 13 is deflected into output tube OL, a portion of the fluidpasses through line 34 into control nozzle 0R4. This resets the fourthamplifier 14 by deflecting the power jet therein from tube 0R4 to tube01.4. At this point, one complete cycle of the timing operation is thencompleted and all four amplifiers are in their Original state with thepower jets being discharged through the output tubes OL. When startingup the timer, the power jet of the first amplifier 11 may be directedinto its left output tube OL by means of a conventional resetting pulsesupplied to the control nozzle CR1 or to a supplementary nozzle on thesame side of the amplifier.

In order to provide an appropriate output signal when a certainpredetermined number of fluid pulses has been applied to the amplifiers,the night hand output tube OR of each amplifier is connected to aselector valve 50. Thus, output tube 0R1 is connected to port 51 of thevalve 50, tube 0R2 is connected to port 52, tube 0R3 is connected toport 53, and tube 0R4 is connected to port 54. The selector valve 50, ismanually set to direct fluid [from the appropriate port into outlet 55.For example, in FIG. 1 the valve is set to use the fluid from port 53 toproduce an output signal, which would indicate the third pulse of eachcycle. It will be apparent that these output signals may be passed intoan adder, as described hereinafter, where multiple cycles are requiredto count the desired number of pulses. Also, while the particularcounter shown in the drawings includes only four bistable amplifiers orswitching elements, it is obvious that the circuit may be expanded toinclude any desired number of amplifiers.

It will be understood that in a complete fluidatimer, a plurality ofcounters such as that shown in FIG. 1 are connected together in acascade arrangement, with the output signals of the various countersbeing fed into an adder. After the total interval indicated by the sumof the various adder input signals has elapsed, the adder triggers anappropriate output transducer to activate the particular device beingtimed, for example, an explosive detonator.

In accordance with a further aspect of the invention, there is provideda fluid-operated adder comprising a series of fluid-operated switchingelements each of which is connected to a different fluid-operatedcounter so as to be switched from one stable state to the other by thetimed fluid pulses from the counter, and biasing means for selectivelycontrolling the switching of the switching elements, the biasing meansfor each switching element being responsive to the switching of thepreceding element in the series whereby the elements are switchedsequentially in timed relation to the timed fluid pulses from thecounter. Thus, referring to FIG. 3, there is provided a series ofhistable fluid amplifiers 71, 72, 73 and 74. These amplifiers aresimilar to those described above in connection with the counter circuitof FIG. 1, each amplifier having a power nozzle P connected to a sourceof pressurized fluid, a chamber R, first and second output tubes 0L andOR leading away from the power nozzle P, and first and second controlnozzles CL and CR opening into the first and second outlet tubesadjacent the orifice of the power nozzle P.

Assuming that the adder of Fig. 3 is to be used to add pulses from fourdifferent counters producing pulses at intervals of 100 seconds,seconds, 1 second and 0.1 second, respectively, the output pulses fromthe four counters are passed into the left hand control nozzles CL ofthe four amplifiers 71, 72, 73 and 74. The pulses having the lowestfrequency, i.e., the pulses with the largest intervals are applied tothe first amplifier 71, while the other pulses are applied to theremaining amplifiers in the order of increasing frequency. For example,to add pulses from the arrangement of four counters mentioned above, the100-second pulses would be applied to the first amplifier 71, thelO-second pulses would be applied to the second amplifier 72, thel-sec-ond pulses would be applied to the third amplifier 73, and the0.1-second pulses to the fourth amplifier 74.

As in the case of the counter circuit of FIG. 1, the power jet of eachof the four amplifiers 71, 72, 73 and 74 is initially directed into itsleft output tube OL. Then when the counter pulses are applied to theleft control nozzle CL, they tend to deflect the power jet away fromtube OL over into tube OR. However, as the power jet from the firstamplifier 71 is discharged through the tube 0L1, the fluid is directedthrough a line 82 into control nozzle CR2 of the second amplifier 72.Similarly,

fluid from output tube 0L2 of the second amplifier is directed through aline 83 to nozzle CR3 of the third amplifier 73, and fluid from the tube0L3 of the third amplifier is directed through a line 84 to nozzle CR4of the fourth amplifier 74. Thus, each of the amplifiers 72, 73, 74 isbiased to the left by the jets emerging from the control nozzles CR2,CR3 and CR4, and the first amplifier 71 is the only one that is notbiased and, therefore, is conditioned for switching.

Because of the biasing of amplifiers 72, 73, and 74, these amplifiersare not switched by any pulses applied thereto prior to the switching ofamplifier 71. When the first pulse is applied to control nozzle CLl ofamplifier 71, that amplifier is switched, and the bias is removed fromthe second amplifier 72. This conditions amplifier 72 for switching sothat the next pulse applied to nozzle CL2 deflects the power jet inamplifier 72 from tube 0L2 to tube 0R2. This removes the bias fromamplifier 73 so that it is conditioned for switching by the next pulseapplied to control nozzle CL3. Finally, after switching of amplifier 73,the bias is removed from amplifier 74, which is switched by the nextpulse applied to nozzle CL4.

It can be seen from the above description that the biasing lines 82, 83and 84 and the right hand control nozzles CR2, CR3, and CR4 act asbiasing or conditioning means which selectively control the switching ofthe bi-stable amplifiers by the applied fluid pulses from the variouscounters. Moreover, each of these biasing or conditioning means isresponsive to the switching of the preceding amplifier so that theamplifiers are switched sequentially in timed relation to the pulsesfrom the various counters.

As each of the first three amplifiers 71, 72 and 73 is switched fromtube OL to tube OR, the fluid in tube OR is dumped to a suitable fluidsink. However, when the fourth amplifier 74 is switched, the fluid fromtube 0R4 is used as the output signal which is fed into an appropriatetransducer. The particular time period represented by this signaldepends on a number of factors, such as the frequency of the originalfluid pulses applied to the counters and the setting of the variouscounter selector valves 50. Thus, if the original pulses were producedat a rate of 10 pulses per second and applied to a cascade of fourcounters each having ten switching elements, and with each of the fourcounter selector valves being set at the first port, the adder outputwould represent a period of 111.1 seconds. Of course, it will beapparent that this period could be varied by simply adjusting thesetting of the selector valves, and would be accurate to values within atenth of a second.

It will be understood that the timed fluid pulses applied through line20 to the ring counter of FIG. 1 may be generated by any suitablesource. One such source is a fluid-operated oscillator such as thatillustrated in FIG. 4.

This oscillator comprises a bi-stable fluid amplifier having a pair offeedback loops 91 and 92. Each feedback loop leads from one of theoutput tubes OL or OR back into the corresponding control nozzle CL orCR. Assuming the power jet initially locks on to output tube 0L, aportion of the fluid leaks into feedback loop 91 and eventually issuesas a control jet from control nozzle CL. This deflects the power jetover into output tube OR, where a portion of the fluid bleeds backthrough loop 92 and issues from control nozzle CR to deflect the jetback to output tube OR. This switching action contimes as long assufficient pressure is maintained in the power jet, with the period offrequency of the oscillator depending on the supply pressure and exhaustpressure, fluid temperature and flow resistance and capacitance of thefeedback loops.

In order to provide the desired oscillator frequency, the feedback loops91 and 92 are provided with capacity chambers 93 and 94, respectively,having corresponding baflles 93a and 94a therein. Also furthermodifications may be made to provide the required frequency stability.For example, in order to compensate for temperature fluctuations, it iscontemplated that the feedback loops may be provided with resistanceand/or capacitance means which expand and contract in accordance withrespective increases and decreases in temperature. Similarly, tocompensate for pressure variations, the source of pressurized fluid mayconsist of a chamber filled with a fluid in both liquid and vapor stateswhereby a constant supply pressure is maintained. It is furthercontemplated that temperature compensation may be provided by expandablechamber walls, if desired.

It will be seen that the invention provides an improved fluid-operatedtimer circuit in which the timed fluid pulses being counted or added areapplied directly to each of the individual switching elements in theparticular circuit involved, rather than being applied to only a singleswitching element and then passed sequentially through the remainingelements. Thus, each switching element is switched only once in eachcomplete cycle, and the response time for any given pulse in aparticular circuit is the response time of only a single switchingelement rather than the cumulative response time of a plurality ofelements. Moreover, the circuits of this invention are positive startingand capable of automatic resetting.

What is claimed is:

1. A fluid-operated counter circuit for use in a fluidoperated timer,said counter comprising, in combination, means for transmittingpressurized fluid, a series of histable fluid-operated amplifiers eachof which has a body defining a jet chamber having a power nozzle at oneend connected to said means for transmitting pressurized fluid toproduce a power jet and having first and second output tubes at theother end, first and second primary control nozzles on opposite sides ofsaid power nozzle, each of the amplifiers between the first and the lastamplifiers of said series also having a secondary control nozzle on thesame side as the second primary control nozzle, a fluid-operatedoscillator connected directly to the first control nozzle of eachamplifier for applying timed fluid pulses thereto, the second primarycontrol nozzle of the first amplifier in said series being connected tothe second output tube of the last amplifier and to the secondarycontrol nozzles of the other amplifiers in said series, the secondprimary control nozzle of each of the other amplifiers being connectedto the first output tube of the preceding amplifier in the series, and aselector valve connected to the second output tube of each of saidamplifiers.

2. A fluid-operated timer circuit comprising, in combination, means fortransmitting pressurized fluid, a plurality of fluid-operated counterseach generating timed fluid pulses at different predeterminedfrequencies, and a fluid-operated adder circuit comprising a series offluidoperated switching elements each of which has a 'body defining ajet chamber having a power nozzle at one end connected to said means fortransmitting pressurized fluid to produce a power jet and having firstand second output tubes at the other end, first and second controlnozzles on opposite sides of said power nozzle, the first control nozzleof each switching element being connected directly to one of saidcounters for receiving timed fluid pulses to switch said element fromthe first to the second state of operation, biasing means operativelyassociated with the second control nozzle of each switching elementother than the first element for selectively controlling the switchingof said elements by said timed fluid pulses from the counters, thebiasing means for each switching element being responsive to theswitching of the preceding element in the series so that said elementsare switched sequentially, and reset means for restoring said switchingelements to the first state of operation.

3. A fluid-operated counter circuit for use in a fluidoperated timersupplied with timed fluid pulses, said counter comprising, incombination, means for transmitting pressurized fluid, a series offluid-operated switching elements each of which has a body defining ajet chamber having a power nozzle at one end connected to said means fortransmitting pressurized fluid to produce a power jet and having firstand second output tubes at the other end, first and second primarycontrol nozzles on opposite sides of said power nozzle, each of theswitching elements between the first and the last elements of saidseries also having a secondary control nozzle on the same side as thesecond primary control nozzle, means for transmitting the timed fluidpulses directly to the first control nozzle of each switching element,the first output tube of each of said switching elements, except thelast element in the series, being coupled to the second pri-mary controlnozzle of the adjacent succeeding switching element so as to bias eachswitching element other than the first element toward its first outputtube until the power jet of the immediately preceding switching elementhas been switched from the first output tube to the second output tu'bewhereby said elements are switched sequentially in timed relation tosaid timed fluid pulses, the second output tube of the last switchingelement in said series being connected to the second primary controlnozzle of the first switching element for resetting the power jets inall said switching elements from the second output tube back into thefirst output tube in response to the switching of the last element.

4. A fluid-operated timer circuit comprising, in combination, means fortransmitting pressurized fluid, a plurality of fluid-operated counterseach generating timed fluid pulses at difierent predeterminedfrequencies, and a fluid-operated adder circuit comprising a series offluidoperated switching elements each of which has a body defining a jetchamber having a power nozzle at one end connected to said means fortransmitting pressurized fluid to produce a power jet and having firstand second output tubes at the other end, first and second controlnozzles on opposite sides of said power nozzle, the first control nozzleof each switching element being connected directly to one of saidcounters for receiving'timed fluid pulses to switch said element fromthe first to the second state of operation, the first output tube ofeach of said switching elements, except the last element in the series,being coupled to the second primary control nozzle of the adjacentsucceeding switching element so as to bias each switching element otherthan the first element toward its first output tube until the power jetof the immediately preceding switching element has been switched fromthe first output tube to the second output tube whereby said elementsare switched sequentially in timed relation to said timed fluid pulses,and reset means for restoring said switching elements to the first stateof operation.

References Cited by the Examiner UNITED STATES PATENTS 6/1963 Warren235201 4/1964 Norwood 235-201 OTHER REFERENCES RICHARD B. WILKINSON,Primary Examiner.

LEO SMILOW, Examiner.

WAYNE F. BAUER, Assistant Examiner.

1. A FLUID-OPERATED COUNTER CIRCUIT FOR USE IN A FLUIDOPERATED TIMER,SAID COUNTER COMPRISING, IN COMBINATION, MEANS FOR TRANSMITTINGPRESSURIZED FLUID, A SERIES OF BISTABLE FLUID-OPERATED AMPLIFIERS EACHOF WHICH HAS A BODY DEFINING A JET CHAMBER HAVING A POWER NOZZLE AT ONEEND CONNECTED TO SAID MEANS FOR TRANSMITTING PRESSURIZED FLUID TOPRODUCE A POWER JET AND HAVING A FIRST AND SECOND OUTPUT TUBES AT THEOTHER END, FIRST AND SECOND PRIMARY CONTROL NOZZLES ON OPPOSITE SIDES OFSAID POWER NOZZLE, EACH OF THE AMPLIFIERS BETWEEN THE FIRST AND THE LASTAMPLIFIERS OF SAID SERIES ALSO HAVING A SECONDARY CONTROL NOZZLE ON THESAME SIDE AS THE SECOND PRIMARY CONTROL NOZZLE, A FLUID-OPERATEDOSCILLATOR CONNECTED DIRECTLY TO